DevTools: keep widgets in widget hierarchy upon hide, split attach/detach cycle from show/hide.

third_party/WebKit/Source/devtools/front_end/ui_lazy/TimelineOverviewPane.js

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 458 matching lines @@
 
 /**
  * @interface
  */
 WebInspector.TimelineOverview = function()
 {
 }
 
 WebInspector.TimelineOverview.prototype = {
     /**
-     * @param {?Element} parentElement
-     * @param {!Element=} insertBefore
+     * @param {!Element} parentElement
+     * @param {?Element=} insertBefore
      */
     show: function(parentElement, insertBefore) { },
 
     update: function() { },
 
     dispose: function() { },
 
     reset: function() { },
 
     /**
@@ skipping 141 matching lines @@
     },
 
     resetCanvas: function()
     {
         this._canvas.width = this.element.clientWidth * window.devicePixelRatio;
         this._canvas.height = this.element.clientHeight * window.devicePixelRatio;
     },
 
     __proto__: WebInspector.VBox.prototype
 }